dieterich



April 2,-1929. L. M. DIETERICH METHOD AND APPARATUS FOR RADIO RECEPTIONFi'led Feb. 19, 1924 2 N 2 9 4/ 3 2 W 4/ 2 Z M7 4 w l r 1 1 1 I a c v 2v H 2 f w \Ta 2 fin u mw H H H H H O ,N MA I- tom W11- 1 l... H, w I"? 2x I E Q A I 7 w w 5 Mm m 9 2 2 p J 2 5 3 O 3 =2 w H m BY (Mai. 631m MaATTORNEY.

Patented Apr. 2, 1929.

UNITED STATES PATENT OFFICE.

LUDXVIG M. DIETERICH, OF NEW BRUNSWICK, NEW JERSEY, ASSIGNOR, BY DIRECTAND MESNE ASSIGNMENTS, TO CHAR-LES V7. WHEELOCK, TRUSTEE, OF NEW YORK,

METHOD AND APPARATUS FOR RADIO RECEPTION.

Application filed February 19, 1924. Serial No. 693,747.

This invention relates to a method and apparatus for the translation andamplification of modulated currents, particularly high frequencyoscillating currents modulated at an audio frequency, such as voicefrequency in the case of telephony. More specifically, this inventionrelates to a method and apparatus for translating with amplification ofalternating currents such as are up in the collectors of radio receivingstations.

C ne of the objects of this invention is to provide a simple, practicaland thoroughly reliable apparatus for detecting or translating modulatedcurrents, particularly such modulated currents as are characteristic,for sample, in the art of transmitting intelligence or subject by radio.Another object of this invention is to provide a simple and compactapparatus for translating with a1nplification modulated currents, and toprovide apparatus of the above-mentioned character which will be ofefficient action, easy of control, simple and convenient manipulation,and ready adjustability. Another objectof this invention is to provideapparatus of the above-mentioned nature which will be not only ofcompact construction, but also of inexpensive manufacture, all withoutdeparting from high efiiciency, reliability and dependability of actionwhen in use. Another object of this invention is to provide apparatusofthe above nature which will be well. acapted to meet the conditions ofhard practical use and which may becontrolled, ii'ianipulated oroperated with the requirement of a minimum amount of skill. Anotherobject of this invention is to provide a thoroughly practical art ofdetecting, translating, or amplifying modulated currents and one whichmay be in practice readily and inexpensively *arried on. Other objectswill. be part obvious or in part pointed out hereinafter.

The invention accordingly consists in the fe tures of construction,combinations of elements, arrangements of parts and in the several stepsand relation and order of each of the same to one or more of the othersall as will be illustratively described herein, and the scope of theapplication of which will be indicated in the following claims.

In the accompanying drawing in which are shown several of variouspossible embodimen ts t the mechanical features of this invention,

Figure 3 is a view similar to that of Figure 2, but showing a modifiedform.

Figure l is a detailed fragn'ientarv view of a part of the apparatusshown in F igure 1, and it is a fragmentary view as seen from the rightof Figure 1.

Similar reference characters refer to simi lar parts throughout theseveral views of the drawing. 7

Referring now to the drawing and more imrticularly to Figure 1, there isshown 1O collector, conveniently taking the form to an antenna connectedthrough a variable inductance 11 to ground 12, the variable inductancel1 permitting the collector circuit to be tuned to any desired frequencyor wave length. A secondary circuit, preferably tunable or adjustable atwill to the dc .l wave length or frequency, comprises preicrably avariable inductance 13, which, with the variable inductance 11, mayconveniently form the coupling betwee: the collector circuit and thesecondary circuit, a condenser 14, which may be fixed, and a condenser15, preferably variable. The coupling between the coils 11 and 13 ispreferably made variable at will. a I

The secondary circuit wave len 'th' of the modulated oscillatingcurrent, tneenergy of which is illustratively shown as being transmittedby radio and hence received by the collector 1.0 and associated primarytuning circuit, but it is to be unoerstood that the energy of themodulated oscillating current may be transmitted in any other convenientor suitable mann-r and suitably transferred to the secondary receiv ingcircuit.

A ring-shaped member 16, preferably made of a suitable insulatingmaterial, and held in rigid position in any suitable manner, supportsrigidly therein acoil 1i", preferably of the pancake type, and having asuitablen ember of turns and preferabl several layers of turns of wiretherein. In

111213 thus be ad usted to the desired frequency or Figure 1 there areillustratively shown four layers oi. turns of wire in this cell 17. theright of the coil 17 and spaced therefrom is a coil 18, also preferablyof the paneali. type, having a suitable number of turns therein and illustratively shown in Figu re 1 as comprising; only a single layer ofturns. The wire of the coil 18 is preferably made of a light metal, soas to maintain the mass of the coil. .18 at a minimum and is supportedby and attached in any suitable n'ianner to a movable member 19 taking'the form preferably ot a metallic, and hence conductive, plate nuanber,it being understood that the several turns of wire in the coil 11.8 areinsulated one from the other and insulated also from the plate memberIll). The plate mem ber 19, moreover, also preferably made of a l' itmaterial, so that the niass thereof is mail tained at a minimum, and theplate member furthermore is preferably so formed and of such material asto have good Vibrat ing or sound reproducing charaeteristics.

Considering now the mounting: oi the plate member 19, it is to be notedfirst that the plate member 19 with the coil 18 thereon are preterablyof disk-like shape, and the outer periphery of the disk plate member 19is supported in a ring member Q0, preferably of insulating material,such as fiber or haltelite, for example. The ring; member 20 is er:-tended to the left as seen in Figure 1 and. at this extended portion isthreadedv interior- ].y as at 20. The threaded portion 20 is in threadedengagement with the exteriorly threaded portion 16 ot the ring mei'nber1b which rigidly supports the coil 17. At this point it may he notedthat the intor-threaded relation between the supporting ring members lband 2t) permit not only a rapid and convenient assembly of the partsandv inure pensive nianu'ii'actare, but also permit of a rapid and atthe same time precise position inp; or adjusting; oi the coil 18 witl'respect to the coil W, in order that the action thercla l'weeu, to bemore clearly hereafter dcscribed, may he made most cllicicntfor givenconditions oi. operation.

blpaccd from the plate member if) and to the right thereof, s viewed inl ippn'e l, mounted a plate member ill, preferably metallic lhrinurhout.and hence conductive, and havino' a thirduess or'oihcr appropriate char.as to give the plate member 21. a substantial rigidity or freedom fromdistortion. l.he plate u'ienibcr 29.1 is supported prejl crablythroughout its periphery by another ring member 22, n'eiterably oil asuitable insulating or non-conductin material and is rigidly securedthereto. 'lhe rinse member 22, however, is extended toward the left, asviewed in Figure l and at this extended portion is interiorly threaded,as at 2:2 in order to be received and threaded upon the exleriorlythreaded portion 20 of the ring member 20. As hercinbefore noted inconnection. with the relation between the ring members 20 and 16, it mayalso, at this point, b pointed out that the threaded relation betweenthe ring member 22 which supports the plate member 21, and the ringmember 20 which supports the plate member 19 likewise permits oi? arapid, but at the same time precise posituininn ot the plate member 21with respect to the plate member 19. Moreover, it will be noted that allof the several parts are rigidly held in assembled position or relationand that by rotating either of the ring members 20 or 22 in eitherdirection, the tlneadcalv relation between these several parts permitsthe ready :nliustnrent oi the several parts for most ellicieut actionfor giyen conditions.

i'he plate member 21., like the plate memalso preterably disk-like inshape ber 19, is

and the plate men'ibers 1S) andfll are preterably oft such dnu'nclers ordimensions as to present adjaccn surfaces o'i sul'istautially equalarea. ll plate inei'nber 521, however, is provided at its centralportion with an opei'iine' 21.- of suitable area and attached to thedisk member 21 and in substantial registry with the opening 2i is asuitable sound box or sound projector 23.

The coils l? and 18 are connected preterably in series with each otheras by the flexible connection or conductor 2 and by means of theconductors 25 and 526 are connected to the receiving; circuit,preferably as by projecting these two coils in series across thecondenser l5. 'lhe coils 17 and 18 may thus be zed by modulated current,and as illustrativcly shown in l i zure Li and illustrativcly herciinilare described, will. be responsive to a high frequency oscillat currentmodulated in accordance with an audio frequency, such as, for or anellevoice irccpiency. The interaction bet ween the ilXQd cells 17 and themovable coil. 18 will thus vary in accordance with the amplitude insubsta-u,

tial ac .:ordance a l h the aunllitnde of the modulated current, butwhere this current is of high trc p1ency, the inertia of the movablecoil .8 anddisk or diaphragm '15), will be such. as to prevent theseparts from \"iln'atino' at the high or carrier frequency. llhe movableparts, however, will iartalie ol a vilnating nioiionconill1(li;.-'lll2llt with the envelope oil? the unidirlaled high'lrequei'icy current, and wl'iere this envelope rcpr ents a voicefrequency, the

I vibrations oi the diaphrag 'in l9 will. repro- .llii

denser, the capacity of which varies with the spacing between the twoplate members. The condenser thus formed by the plates 19 and 21 isincluded in a circuit having therein a source of current 27 of suitablepotential, the flow of current from which is governed by the variationin the capacity between the plates 19 and 21. Thus a conductor 28connects the source 27 to one plate 21) of this condenser, a conductor29 connects the other plate (19) of this condenser to the other side ofthe source 27 but through the primary winding 30 of a transformer 30-31and through an adjustable resistance 32. The secondary vinding 31 of thetransformer 30-31 is substantially bridged across the coils 1'? and 18,and in Figure 1 is shown connected to or bridged across these coilsthrough the inductance 13. The transformer EEO-31 preferably contains aniron core not only to prevent the passage through the secondary winding31 of the high frequency modulated current, which is by-passed throughthe condenser 141, but also to insure an eflicient transformation of thedirect current from the auxiliary source 27, varying at the frequency ofmodulation, into an alternating current of commensurate frequency fordirect action upon the diaphragm moving coils 17 and 18. Thus, as thediaphragm 19 vibrates and hence varies the spacing between the condenserplates 19 and 21, the leakage current flowing between these two platesand hence through the primary winding 30 of the transformer 30-31partakes of variations connnensurate with the rate or frequency ofvibration of the diaphragm 19. The energy thus variably controlled fromthe auxiliary source, illustratively shown as being a direct currentsource, is thus made to supplement the initial energy received from thecollector or other transmitting circuit and is effective to cause theinitial vibration of the diaphragm 19. The vibration of the latter isthus materially reenforced or enhanced, and the corresponding soundwaves materially increased and an'ipliiicd, these sound waves beingprojected through the sound box 23.

It may b pointed out that the several parts, such as the coils and platemembers, each preferably dislnlike in shape or form, a by the cinstruct-ionv lwreinbefore de scribed, ell'ectively held insubsz'nutially parallel. relation with respect to one another and thatthis parallel rel ation is maintained. irrespective of the adjustmentsthat may be given one of the parts with respect to the other. Thediaphragm 19 may vibrate as by deflections, but it is preferablyarranged to vibrate also bodily toward or away from the relatively fixedplate member 21. Thus, referring still to Figure 1 the ring member 20 isprovided with an annular groove or recess 2O between the spaced sidewalls of which is received the diaphragm 19, but between which and thediaphragm are interposed the resilient or yielding supporting rings 20and 20 one on each side of the diaphragm 19. These supporting rings arepreferably of readily yieldable rubber, and are-tapered toward thediaphragm as is clearly shownin Figure 1 in order to permit a readyvibrating movement bodily of the diaphragm 19 in a directionsubstantially transverse to its own plane. The plate member 19 may thusbe held substantially parallel to itself and to the cooperating platemember 21, throughout its vibratory movements, and by this arrangementthere is achieved not only a highly effective vibration of theintervening other or atmosphere, thereby to set up effectivelycmrresponding sound waves, but also an eiiicientvariation in thecapacity between the two plates 19 and 21. It is to be understood,however, that the sound Waves may be set up or produced by the vibratingdiaphragm 19 not only by the bodily or piston-like vibrations thereof,but also by such inherent vibrations of the diaphragm as may becharacterized by deflections of the diaphragm 19, or both; and it ispointed out furthermore that the term vibration orvibrating is here inintended to be used broadly to comprehend either or both of theseabove-mentioned sound producing movements in or of the diaphragm 19.

From the foregoing it is believed that the operation of the apparatuswill be clearly understood; it may be pointed out, however, that Iprefer to make the apparatus more sensitive in its control of the energyfrom the auxiliary source and for this purpose I ma f adopt anarrangement illustrativel shown in Figure 2. In this figure there isshown an enlarged scale a fragmentary portion of the vibrating diaphragm19 with the coil 18 associated therewith, and the fixer plate memberdesignated at 21. ()no of these plate members, such as and preferablythe stationary or fixed plate member 21 I provide with a series ofprojecting points 21 on that face of the plate which is adjacent thecooperating plate member. These points 21 may be of any suitable numberand are preferably not only of substantially uniform le gth, but also ofsubstantially uniform disx bution throughout the face of the platemember 21*. These points 21 greatly fa ei.it:'.te the flow of thedisplacement current from one plate to the other, and may be con sideredas permitting the flow of current between the two plates to partake ofthe nature of a brush discharge.

1 may, however, also substantially COIlCGIl trate or restrict the pathof flow of the condenser leakage current by substantially concentratingthe projections on one of the plates, and thus for example, I mayutilize the arrangement shown in Figure 3, in which one of the platemembers, such as the station till pro ect riegz-ehuped edge may thusZICL to tieihtute the pier-seep ot the loultege current tr one plate tothe other end this may tuh p re even also in the form ojif u hruuhdiuchurgge. This letter urreug eu'ieet, shown in ll igg'ure 3, isruirticulurly advantageous Where the round i ii'oduciug iueinherper-tithes o't deflections or dis-ztorrious it vibrates, it lmiilfjjuuderutood that, Where the vibrating member is; dis -like in shape, suchdeflectiouul rile,"

tioiis tl'icreot are most etiective or have tlu V Miter-u, amplitude fitthe center of the (l up noggin, :uid thut in relu the projecting:1ll1"l]'1l)t=t', 5118i], us the ringer shaped meeiher ill, in the regionWhere the ztml i it'iltie of the iuovzwhte meiuher it u more inuun thereiri uchiered uot only a repid or quichl 1 reepouuir action, but also :1iti'euter iutei of flow in the disp acement or leel-zug 'e current.

It will thus he soon that he lEt rent they he greatly intensified enaction oi the 'trzihreformer 30-l; roruiiogg on inductive couplingbetween the iceiviiig; circuit and the circuit 0t th auxiliary source,

I, us; illustrative of u possihle "one o't coupling that may heemployed, is made highly ell'eetive in ti'uueterrieg e lurgi'e uiiiouirtot' euerer from the letter circuit to the diziphruggiu inorijiuz coil oreoilu. fir; her ,inheit.

re noted, the coils 18 rod 1.?

iuiy' he :uliuuted relatively one to t r ie other convenient iueuuu tor:

i u order i i to opmoot proridev; :i I iligi thr- (fmHltth--'tl' to thepotential oi liu iury :uuuce, i!i2istrzitively thoeu :tie it do urrrutueurce in the hotter 3i";

moreovru', thin :uliuetmez e rewiring; he tween the plate ureuihe llpermits: :ui emu; )rmleterr'uouti rule comi L m. to he 11 l el. oil the7 energy transfer i form of u leulo tha pr 22- ur -;ouree so 21:5; tomaintain between. the two pl tee in ego current or even u brusheischzirge, but. to

prevent it diuruptive disclu In this conuurv I iieetiou also it noted tmt the variable r s'oteece 2-32 terms" at convenient ud ustehlehuluneing resistance to prevent disrupted diechorges, it being notedthat u disrupted diecl'uirge is in. geuerul preceded by brush dischargeand that the hot i of the current corresponding to this brush dischargeinsures a slight Voltage drop in the holiest resistance 32. There thusinsured a, slight drop in potential between the two plates and thetransitioii from o brush discharge to disrupted (llS- charge is thusetl'ectively avoided or prevented.

Each of the ring members end 22 is eplit rediully a convenient point inthe circumference thereof in order to permit the ring; members, utterrelative adjustment, to he clumped upon their couctiiig threadedmembers, thus to lock the ports in adjusted position. In Figure l isshown 'l rugmenturily one of these members such as the ring 111cmher 22proviced with u cut or slit 22, and W5 irh 'he outwurdl projectingshoulders 22 turd 2:13, :ulupted to he drawn together as by uuping screw22" threaded into one of rod adopted to permit 2i contraction of I r ith iii the ring member to clump it into piece.

From the foregoing, the manner of prectieing my invention will he eleur;as eouducive, however, to u poesihle clearer understuudingr of certainactions that take plece, ee tuiu theoreticei considerations might be setforth. 'lihe capacity C of e eoud ueer the quotient oi the numericalvalue oi: the charge Q, on either conductor or plate of the coudenser bythe difference of potential V betwe u. the two conductors when equu.ftlld. opposi to charges a ,7 n the. cmiductorss, i. 0., (l V. Fl'flli'lthis relation it follows that the potential diilerence V across the twocori- (h-zctors become/v; l/C. The condenser ilforiued hy the plates 1.)and 21. ot' the ZLPlXU'ttllS hereiouhove d ihed, hitting Tier-u in? illylequent uu'weiueut oi? oi charged, :1 e1. 1 the plates or dluphrz nu;With respect to t i r he that there in to 21, as will i the reuultuiit)O't'CDi'iPl diliii, i oce l (tween the plutes; l9 :UHl .Z'l is thusmade greater or lees: their the \(Ell'ilgit of the source of potential157, there resulte in the correupmul 11? circuit 21 lieu of currentvery- 1- .l

io in one 1;! 'ctiou or the other, and through the priuutry winding (iiithe runsiormer se i-u. 'lhe reuchiu ol the current in the primaryeluding 30 upon the see coiulur Windiugg; Bl and of the letter upon therenuiiuiug }')()lt3l0i -i oi the circuit Will he clear from what l 2 14hereiiihcitore been set forth in detail. lit

in in any conuy further he pointed ou tl denser, Where the etreligth oi?the dielectric heir between the TWO pletes 1S VttlflQfl or need, theretakes piece it less of energy in the dielectric, This phenomena isanalogous t magnetic hystereeie edit]. the losses thus generated are, ofcourse, supplied from the source energizing the condenser. While such aloss is ordinarily present and recognized where the change in thedielectric field of a condenser takes place due to changes in thepotential applied to the two plates thereof, yet in the apparatushereinabove described the change in the dielectric field is broughtabout by the continuous change in the relative position of the plates 19and 21, in turn brought about by the vibration in audio frequency of theone with respect to the other. Such ava riation in the dielectric fieldat an audio frequency rate causes the dissipation of energy in thedielectric field and the corresponding loss is supplied by a currentflow from the source of potential 27, and hence through the primarywinding 30 of the transformer 30-31. This latter current from the source27 which supplies the losses just mentioned may supplement the actionimmediately above described according to which, as above noted, thechanges in the capacity C, due to the vibration of the one plate withrespect to the other, cause a varying current flow through the primarywinding 30 of the transformer.

It will thus be seen that there has been provided in this invention asimple and thoroughly practical method and apparatus for translating andamplifying modulated currents. It will furthermore be noted that theapparatus is of simple and compact construction, of simple manipulationand adjustment and of thoroughly relia lo and dependable actionthroughout. It will also be noted that the method provided by thisinvention may furthermore be readily and inexpensively carried out inpractice and with highly citicient and dependable results. It willalso'be seen that the several objects of this invention, together withmany advantages are successfully achieved.

As many possible embodiments might be made of the mechanical features ofthe above invention and as the method herein described might be variedin various particulars, all without departing from the scope of theinvention, it is to be understood that all matter described. herein andshown in the accompanying drawing is to be interpreted as illustrativeand not in a limiting sense.

I claim as my invention:

1. The herein described art which consists in utilizing the energy of ahigh frequency oscillating current modulated at audio equency to producemotion in a member at substantially the audio frequency rate, utilizingthe motion of said member to cause a current flow varying in intensitysubstantially at the said audio frequency rate, and utilizing saidvariable current flow to increase the amplitude of the motion in saidmember.

2. The herein described art which consists in utilizing the energy ofthe high frequency on rent to vary the distance between two spacedconductive members at the frequency of modulation, utilizing thevariatlon 1n spacing between said two conductive mom here to vary thedisplacement current flow therebetween and from an auxiliary source, andin supplementing the energy of the modulated high frequency current withenergy from said auxiliary source proportional to the said variabledisplacement current.

3. The herein described art which consists in utilizing opposed magneticeflects of the modulated current to produce motion in a member,utilizing the motion of said member to control the flow of energy froman auxiliary source, and in supplementing said opposed magnetic effectsof the modulated current with opposed magnetic effects of the controlledcurrent from said auxiliary source.

4. The herein described art which consists in utilizing opposed magneticeffects of the modulated current to produce motion in a member at thefrequency of modulation, utilizing the motion of said member to producefrom an auxiliary source a current of the frequency of modulation, andin superimposing the energy of the current from said auxiliary sourceupon said modulated current to increase the amplitudeof motion in saidmemher.

5. The herein described art which consists in utilizing opposed magneticeffects of the modulated current to produce motion in a member at thefrequency of modulation, utilizing the motion of said member to producefrom an auxiliary source a current of the frequency of modulation, andin utilizing the energy of the current from said auxiliary sourcesuperimposed upon the modulated current to produce opposed magneticeffects of the current from said auxiliary source to increase theamplitude of motion in said member.

6. The herein described art which consists in utilizing the energy ofthe n'iodulated current to vilu'ate a souml reproducing member,utilizing the motion of the said sound reproducing member to control theflow of energy from an auxiliary soureeat a variable rate corres gondingsubstantially to the vibration of said member, and in superimposing theenergy of the modulated current upon the energy from said auxiliarysource to vibrate said member.

7. The herein described art which consists in causing the energy of amodulated current to vibrate a conductive sound reproducing member andto vary the spacing thereof from a relatively fixed conductive member,each at substantially the frequency of modulation, utilizing thevariation in spacing between two said conductive members to vary thedisplacement current flowing therebetween and from an auxiliary source,and in utilizing energy from said auxiliary source and proportional tosaid displacement current to alfect aver,

the vibration of said sound reproducing member.

8. ln, apparatus of the character described, in combination, adiaphragm, a coil mounted to more with said diaphragz m, electromagneticmeans coactinp; With said coil to cause vibrations of said diaphragn'i,an auxiliary source of current, means responsive to the vibrations ofsaid diaphragm for causing variations in the flow of current from saidauxiliary source, and means for energizing; said electromaguetic meansby energy dcrived from said auxiliary source.

5). in apparatus of the character (i611 .ribcd, in. combination, a pairof spaced conductive members, adapted to form a capacity, one of whichmembers is movable relative to the other, means l'cspons 'c to amodulated current for moving one of said members with respect to theother, a local circuit including an auxilia y soruce of current and saidtwo spaced members, and means for affecting); the movement of saidmovable member and rcsponsive to the flow of current in said localcircuit.

10. In apparatus of the character dcscribed, in combination, a pair ofspaced oon (luctive members adapted to form a capacity, one of whichmembers is movable With respect to the other, means responsive to amodulated current for vibrating; one of said. members at substantiallythe frequency of modulation, electromagnetic means for atfecting thevibration of said movable member and including; an auxiliary source ofcurrent, the current output of "which is controlled by the variation inthe capacity between said two spaced members.

11. In apparatus of the character described, in combination, areceiving, circuit adapted to be responsive to a modulated highfrequency oscillating current, a movable member, electroiniuqnetio meansadapted to be energized from said receiving; circuit and adapted to ali'ect said movable member to vibrate at sub si on lial ly the frcqurucyof modulation of said oscillating Cl,ll.'l(-.llil, an auxiliary sourceof current, and means responsive to the vibrations of said movablemember and adapted to cause vamiatious in the llow of current from saidauxiliary source at a rate substantially erpiivalcnt to the frequency ofmodulation of said oscillatiru; current, said elcct-romagn 'c moans beiup; responsive to the varying current from said auxiliary source,thereby toreenforce the viln'ations of said movable meuibcr.

12. in apparatus of the character dos ribcd, in combination, adiaphragm, means responive to a modulated high frequency oscillatinccurrent for vibrating said diaphragm at a rate substantially equivalentto the frequency of modulation of said oscillatin cur.- rent, arelatively fixed member arranged in spaced relation from said diaphragmand adapted to form therewith a capacity, an

aiuriliary source of current having: included in the circuit thereof thecapacity formed by said two members, and means res-:ponsive to the flowof current between said. two spaced members for aiecting the vibrationof said diaphragm.

13. in apparatus of the cluiractcr described, in combination, a movableconductive plate member, electromagnetic means adapted to be responsiveto a modulated high frequcrr cy oscillating current for vibrating saidplate member at a rate substantially equivalent to the frequency ofmodulation of said oscilating; current and adapted also to be responsiveto a current of trcquency commensurate with the fr-i-zqucncy ofuuululalion, a relatively fixed plate men'ibcr arranged in spacedrelation from said first-mentioned plate member and adapted to formtherewith a capacity, an auxiliary source of current hav ing; includedin the circuit thereof the capac ity formed, by said. two plate members,and means for energizing said electromagnetic means with energy fromsaid auxiliary source.

14. In apparatus of the character described, in coml'iination, a movablemember, clcctromagnetic means for vibrating said member and adapted tobe responsive to a modulated high frequency oscillating current and alsoto a low frequency alternating current, an. auxiliary source of directcurrent, means responsive to the vibrations of said member for causing;variations in the flow of current from said auxiliary source at a ratesubstantially commensurate with the frequency of modulation of saidoscillating; current, means for converting said varying direct currentfrom said auxiliary source into a lovv frequency alternating current,and means for energizing said electromagnetic means with said. lowtlrequency alternating current.

15. In apparatus of the character dcscribcd, in combination, a movableplate member, olcctroinaguctic means for vibrating said plate member andadapted to be responsive both to a modulated high frequency oscillatingcurrent and. a current of a frequency commensurate with the frequency ofmmlulation of said oscillating current, a relatively fixed plate memberarranged in spaced relation relative to said movable member and adaptedto form therewith a capacity, an auxiliary source of direct currenthaving included in the circuit thereof a capacity formed by said twoplate members, whereby the flow of current from said auxiliary source ismade to vary at a rate substantially equivalent to the frequency ofmodulation of said high frequency current, means for converting thevariable direct current from said auxiliary source into an alternatingcurrent, and means for energizing said. electromagnetic means With thederived alternating current.

16. In apparatus of the character dellO scribed, in combination, a pairof spaced conductive members adapted to form a capacity, one of whichmembers is movable with respect to the other to vary the capacity ofsaid two members, means responsive to a modulated current for vibratingsaid movable member, thereby to vary the capacity between said twomembers at substantially the frequency of modulation of said current, anauxiliary source of current having included in the circuit thereof thecapacity formed by said two members, means responsive to the flow ofcurrent from said auxiliary source for affecting the vibration of saidmovable memher, and means for adjusting the spacing be tween said twomembers.

17. In apparatus of the character described, in combination, a pair ofspaced conductive members adapted to form a capacity, one of whichmembers is movable with respect to the other to vary the capacity ofsaid two members, means mounting said movable member with respect to theother to permit bodily movement thereof toward or away from the other,means responsive to a modulated current for bodily vibrating saidmovable member at a rate substantially equivalent to the frequency ofmodulation of said current, an auxiliary source of current havingincluded in the circuit thereof the capacity formed by said two members,and means responsive to the flow of current from said auxiliary sourceand through said capacity for affecting the vibration of said movablemember.

18. In apparatus of the character described, in combination, a pair ofspaced conductive members adapted to form a capacity, one of whichmembers is movable with respect to the other to vary the capacity ofsaid two members, means mounting said movable member with respect to theother to permit bodily movement thereof toward or away from the other,means responsive to a modulated current for bodily vibrating saidmovable member at a rate substantially equivalent to the frequency ofmodulation of said current, an auxiliary source of current havingincluded in the circuit thereof the capacity formed by said two members,and means responsive to the flow of current from said auxiliary sourceand through said capacity for affecting the vibration of said movablemember, and means for adjusting the spacing between said two members.

19. In apparatus of the character de scribed, in combination, a pair ofspaced conductive members adapted to form a capacity, one of whichmembers is movable with respect to the other to vary the capacity ofsaid two members, means mounting said movable member with respect to theother to permit bodily movement thereof toward or away from the other,means responsive to a modulated current for bodily vibrating saidmovable member at a rate substantially equivalent to the frequency ofmodulation of said current, an auxiliary source of current havingincluded in the circuit thereof the capacity formed by said two members,and means re sponsive to the flow of current from said auxiliary sourceand through said capacity for affecting the vibration of said movablemember, and means for facilitating the flow of leakage current from oneof said members to the other.

20. In apparatus of the character described, in combination, a pair ofspaced conductive members adapted to form a capacity, means responsiveto a modulated current for causing a vibration in one of said members,thereby to vary the capacity therebetween at a rate substantiallyequivalent to the frequency of modulation of said current, a relaycircuit having included therein an auxiliary source of current and thecapacity formed by said two members, and means for facilitating the flowof leakage current from one of said members to the other.

21. In apparatus of the character described, in combination, a pair ofspaced conductive members adapted to forma capacity, means responsive toa modulated current for causing a vibration in one of said members,thereby to vary the capacity there between at a rate substantiallyequivalent to the frequency of modulation of said current, a relaycircuit having included therein an auxiliary source of current and thecapacity formed by said two members, and projecting means on one of saidmembers and extending toward the other for facilitating the flow of lakage current from one of said members to the other.

22. In apparatus of the character described, in combination, a movablemember, a. coil mounted to move with said diaphragm, a relatively lixcdcoil in circuit with said lust-mentioned coil, said two coils beinadapted when one izer by a modulated cur rent to cause role ve movementtherehetween at a rate substantially commci ate with the frequency ofmodulation 01 d current, an auxiliary source of current, meansresponsive to "the movement between said two coils for variablycontrolling the iiow of current from said auxiliary source and at a ratesub stantially equivalent to the frequency of the relative movementbetween said two coils, and means for energizing said two coils withenergy supplied by the variable flow of current from said auxiliarysource.

23. In apparatus of the character described, in combination, a movablemember, a coil mounted to move with said diaphragm, a relatively fixedcoil in circuit with said firstmentioned coil, said two coils beingadapted when energized by a modulated current to cause relative movementtherebetween at a rate substantially commensurate with the freqnmmy of'rnodul'atioh '61 said zmwent, :1 Telnti V0, fixed number aii'angud inspaced relation with ms 115% 0521M first-1m'11ti im 1mm hv'u :mdafllqited "in foil-n1, therewith a capacity, M1 zmxiliniy sofllf'c'e ofcurrent having inch'ldled in H10 circuit fhaywf the capacity formed n$111M [W0 member whereby the 30W 0'? Gin-rent j il n Shh": a izl'i'ysource vmiw :11; :1 min substantially r-rplimlunt 110 the frequency ofrelative nmvmnem bxatwebn 10 said two Inemberss', and ,mezms foremn'gimng said two coils 'Witli mw-crggy derivd from the vni'ying flm'vof current from sait i :mxilimy source.

LU'DWI'G M. DHETERIJH.

